Insights into the structure-property-activity relationship in molybdenum-doped octahedral molecular sieve manganese oxides for catalytic oxidation

Homer C. Genuino, Diego Valencia, Steven L. Suib*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

6 Citations (Scopus)

Abstract

Hexavalent molybdenum ions substituted into the mixed-valent framework of octahedral molecular sieve manganese oxides (1-10 mol% Mo-K-OMS-2) were systematically prepared via a single-step refluxing method. The structure, composition, morphology, thermal stability, and textural and redox properties of the Mo-K-OMS-2 materials were characterized by various experimental techniques. Density functional theory (DFT) calculations were performed to study the electronic properties of K-OMS-2 materials, including the influence of molybdenum on such properties. The catalytic activity of K-OMS-2 towards CO oxidation dramatically increased with Mo dopant concentration, until an optimum incorporation of 5 mol% was reached, giving full CO conversion at 120 degrees C (1 vol% CO, 1 vol% O-2). More importantly, the activity of the 5% Mo-K-OMS-2 catalyst was (reversibly) inhibited by water vapour (3%) in the feed only at low temperatures and exhibited better tolerance and stability during long-run experiments (28 h) as compared to undoped K-OMS-2. The superior performance of Mo-K-OMS-2 catalyst for CO oxidation can be attributed to the following factors: (1) morphological evolution from nanofibers to nanospheres, as well as the slightly distorted structure, generated a sharp increase in the specific surface area up to 258 m(2) g(-1), hence, increased the number of surface active sites; (2) improved mobility of reactive oxygen species at the surface and enhanced redox properties; and (3) tailored electronic properties promoted more active sites for oxidation reactions, which is supported by DFT calculations.

Original languageEnglish
Pages (from-to)6493-6502
Number of pages10
JournalCatalysis Science & Technology
Volume8
Issue number24
DOIs
Publication statusPublished - 21-Dec-2018

Keywords

  • CO OXIDATION
  • LATTICE OXYGEN
  • OMS-2 CATALYST
  • METAL-OXIDES
  • CRYPTOMELANE
  • HOLLANDITE
  • EFFICIENT
  • SILVER
  • AG
  • NANOFIBERS

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